Highlights

Charcoal is highly resistant to degradation and can act as long-term carbon sink. Using an experimental boreal wildfire the authors provide, for the first time, a complete quantification of the biomass carbon that is converted to charcoal instead of emitted to the atmosphere. If scaled up, their results translate into a five times greater charcoal production by wildfire in the global boreal regions than estimated previously.

David Grémillet and coauthors studied little auks, the smallest, yet most numerous seabird of the Arctic, at their northernmost breeding location on Franz-Josef Land (FJL), Russian Arctic (80°N). Using satellite images recorded since 1979, they show that the FJL archipelago has been virtually sea-ice free each summer since 2001. Little auks lost their sea-ice associated zooplankton prey, but switched to feeding inshore. Such unforeseen predatory strategies complicate forecasts of future ecosystem dynamics in a warming Arctic.

Leaf senescence, which leads to leaf fall, is the last stage in the lives of leaves. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. On average, climatic warming will delay and drought will advance leaf senescence. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. Changes in nutrient resorption will impact production in the following year, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling.